* {
    box-sizing: border-box;
    text-align: center;
    margin: 0;
    padding: 0;
}
html,body{
    height: 100%;
}
body{
    background: url("https://pic1.imgdb.cn/item/6357f57916f2c2beb1049df7.jpg");
    /*background-image: url("/images/wallpaper_09.jpg");*/
    background-size: 100% 100%;
    background-attachment: fixed;
}
/*@font-face {*/
/*    font-family: "Tian_Yingzhang";*/
/*    src: url("/Tian_Yingzhang_running_script.ttf");*/
/*}*/
#container{
    min-height: 100%;
    display: flex;    /*容器为flex布局*/
    flex-direction: column;  /* 方向为纵向，保持正常的从上到下文档流 */
}
header,footer{
    color: #fff;
    padding: 20px;
}
header{
    background-color: #FF770F;
    position: sticky;              /*加上"top: 0"将header固定在顶部*/
    top: 0;
    z-index: 2;                 /* z-index的值越大，越优先显示在最上层 */
}
main{
    padding: 20px;
    display: flex;
    flex-direction: column;
    border: 1px dashed #9dff00;
}
footer{
    margin-top: auto;     /* 设置footer的上外边距为auto */
    background-color: #000010;
    width: 100%;
    /*position: sticky;              !*加上"bottom: 0"将footer固定在底部*!*/
    /*bottom: 0;*/
    /*z-index: 2;                 !* z-index的值越大，越优先显示在最上层 *!*/
}
#div_student,#currentTime{
    text-align: left;
}
#div1,#div2,#div3{
    display: inline-block;     /*设置div为行内样式*/
}
#div1{
    float: left;
}
#div2{
    float: contour;
}
#div3{
    float: right;
    width: 250px;
    height: 40px;
}
div.chapter{
    padding-top: 30px;
}
ul{
    margin: 0 10px;
    background: burlywood;
}
li{
    height: 130px;
    padding: 0;
    float: left;
    margin-bottom: 1px;
    margin-top: 1px;
    list-style: none;
    outline: none;
    width: 20% !important;
    border-radius: 30px;          /*圆角*/
}
li.empty{
    background: #cef8d0;
    position: relative;
    text-align: center;
    opacity: 0.6;                 /*透明度(0~1)*/
}
li.empty:hover{                   /*鼠标悬停时*/
    opacity: 0.8;
}
li.double{
    background: #f6dac5;
    display: flex;
    justify-content: center;      /*水平居中*/
    align-content: center;        /*垂直居中*/
    position: relative;
    box-shadow: 4px 8px 8px hsl(0deg 0% 0% / 0.25);       /*阴影*/
    opacity: 0.8;
}
li.double:hover{
    opacity: 0.9;
}
ul li.double a p{
    font-size: 25px;
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%,-50%);

}
a,abbr{
    text-decoration: none;   /*去链接下划线*/
}
.ch04,.ch05,.ch06,.ch07,.ch08,.ch10,.ch_test{
    width: 100%;
    height: 100%;
    border-radius: 30px;
}
/* a:hover鼠标悬停其上时的链接样式 */
ul li a:hover{
    background-color: #f8ba8a;
}
#div_student{
    display: flex;
    flex-direction: row;
    align-items: flex-start;
}
.p_student,.h4_student,.h4_studentID{
    display: inline;       /* 去掉自动换行 */
}
.h4_student{
    font-family: 全新硬笔行书简,华文行楷,楷体;
}
